This invention relates to novel multiple gas discharge display/memory panels or units which have an electrical memory and which are capable of producing a visual display or representation of data such as numerals, letters, television display, radar displays, binary words, etc.
Multiple gas discharge display and/or memory panels of one particular type with which the present invention is concerned are characterized by an ionizable gaseous medium, usually a mixture of at least two gases at an appropriate gas pressure, in a thin gas chamber or space between a pair of opposed dielectric charge storage members which are backed by conductor (electrode) members, the conductor members backing each dielectric member typically being transversely oriented to define a plurality of discrete gas discharge units or cells.
In some prior art panels the discharge units are additionally defined by surrounding or confining physical structure such as by cells or apertures in perforated glass plates and the like so as to be physically isolated relative to other units. In either case, with or without the confining physical structure, charges (electrons, ions) produced upon ionization of the elemental gas volume of a selected discharge unit, when proper alternating operating potentials are applied to selected conductors thereof, are collected upon the surfaces of the dielectric at specifically defined locations and constitute an electrical field opposing the electrical field which created them so as to terminate the discharge for the remainder of the half cycle and aid in the initiation of a discharge on a succeeding opposite half cycle of applied voltage, such charges as are stored constituting an electrical memory.
Thus, the dielectric layers prevent the passage of substantial conductive current from the conductor members to the gaseous medium and also serve as collecting surfaces for ionized gaseous medium charges (electrons, ions) during the alternate half cycles of the A.C. operating potentials, such charges collecting first on one elemental or discrete dielectric surface area and then on an opposing elemental or discrete dielectric surface area on alternate half cycles to constitute an electrical memory.
An example of a panel structure containing non-physically isolated or open discharge units is disclosed in U.S. Pat. No. 3,499,167 issued to Theodore C. Baker, et al.
An example of a panel containing physically isolated units is disclosed in the article by D. L. Bitzer and H. G. Slottow entitled "The Plasma Display Panel -- A Digitally Addressable Display With Inherent Memory", Proceeding of the Fall Joint Computer Conference, IEEE, San Francisco, California, November 1966, pages 541-547. Also reference is made to U.S. Pat. No. 3,559,190.
In the construction of the panel, a continuous volume of ionizable gas is confined between a pair of dielectric surfaces backed by conductor arrays forming matrix elements. The cross conductor arrays may be orthogonally related (but any other configuration of conductor arrays may be used) to define a plurality of opposed pairs of charge storage areas on the surfaces of the dielectric bounding or confining the gas. Thus, for a conductor matrix having H rows and C columns the number of elemental discharge units will be the product H .times. C and the number of elemental or discrete areas will be twice the number of such elemental discharge units.
In addition, the panel may comprise a so-called monolithic structure in which the conductor arrays are created on a single substrate and wherein two or more arrays are separated from each other and from the gaseous medium by at least one insulating member. In such a device the gas discharge takes place not between two opposing electrodes, but between two contiguous or adjacent electrodes on the same substrate; the gas being confined between the substrate and an outer retaining wall.
It is also feasible to have a gas discharge device wherein some of the conductive or electrode members are in direct contact with the gaseous medium and the remaining electrode members are appropriately insulated from such gas, i.e., at least one insulated electrode.
In addition to the matrix configuration, the conductor arrays may be shaped otherwise. Accordingly, while the preferred conductor arrangement is of the crossed grid type as discussed herein, it is likewise apparent that where a maximal variety of two dimensional display patterns is not necessary, as where specific standardized visual shapes (e.g., numerals, letters, words, etc.) are to be formed and image resolution is not critical, the conductors may be shaped accordingly, i.e., a segmented display.
The gas is one which produces visible light or invisible radiation which stimulates a phosphor (if visual display is an objective) and a copious supply of charges (ions and electrons) during discharge.
In prior art, a wide variety of gases and gas mixtures have been utilized as the gaseous medium in a gas discharge device. Typical of such gases include CO; CO.sub.2 ; halogens; nitrogen; NH.sub.3 ; oxygen; water vapor; hydrogen; hydrocarbons; P.sub.2 O.sub.5 ; boron fluoride; acid fumes; TiCl.sub.4 ; Group VIII gases; air; H.sub.2 O.sub.2 ; vapors of sodium, mercury, thallium, cadmium, rubidium, and cesium; carbon disulfide; laughing gas; H.sub.2 S; deoxygenated air; phosphorus vapors; C.sub.2 H.sub.2 ; CH.sub.4 ; naphthalene vapor; anthr cene; freon; ethyl alcohol; methylene bromide; heavy hydrogen; electron attaching gases; sulfur hexafluoride; tritium; radioactive gases; and the rare or inert gases.
In one preferred practice hereof, the gas mixture comprises at least one rare gas, more preferably at least two rare gases, selected from neon, argon, xenon, krypton and radon. Beneficial amounts of mercury and/or helium may also be present.
In an open cell Baker, et al. type panel, the gas pressure and the electric field are sufficient to laterally confine charges generated on discharge within elemental or discrete dielectric areas within the perimeter of such areas, especially in a panel containing non-isolated units.
As described in the Baker, et al. patent, the space between the dielectric surfaces occupied by the gas is such as to permit photons generated on discharge in a selected discrete or elemental volume of gas to pass freely through the gas space and strike surface areas of dielectric remote from the selected discrete volumes, such remote, photon struck dielectric surface areas thereby emitting electrons so as to condition at least one elemental volume other than the elemental volume in which the photons originated.
With respect to the memory function of a given discharge panel, the allowable distance or spacing between the dielectric surfaces depends, inter alia, on the frequency of the alternating current supply, the distance typically being greater for lower frequencies.
While the prior art does disclose gaseous discharge devices having externally positioned electrodes for initiating a gaseous discharge, sometimes called "electrodeless discharge", such prior art devices utilized frequencies and spacings or discharge volumes and operating pressures such that although discharges are initiated in the gaseous medium, such discharges are ineffective or not utilized for charge generation and storage at higher frequencies; although charge storage may be realized at lower frequencies, such charge storage has not been utilized in a display/memory device in the manner of the Bitzer-Slottow or Baker, et al. invention.
The term "memory margin" is defined herein as ##EQU1## where V.sub.f is the half amplitude of the smallest sustaining voltage signal which results in a discharge every half cycle, but at which the cell is not bi-stable and V.sub.E is the half amplitude of the minimum applied voltage sufficient to sustain discharges once initiated.
It will be understood that basic electrical phenomenon utilized in this invention is the generation of charges (ions and electrons) alternately storable at pairs of opposed or facing discrete points or areas on a pair of dielectric surfaces backed by conductors connected to a source of operating potential. Such stored charges result in an electrical field opposing the field produced by the applied potential that created them and hence operate to terminate ionization in the elemental gas volume between opposed or facing discrete points or areas of dielectric surface. The term "sustain a discharge" means producing a sequence of momentary discharges, one discharge for each half cycle of applied alternating sustaining voltage, once the elemental gas volume has been fired, to maintain alternate storing of charges at pairs of opposed discrete areas on the dielectric surfaces.
In accordance with the practice of this invention, there is incorporated into the dielectric of a gas discharge device a beneficial amount of a source of at least one transition element selected from V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Pd, and Pt.
As used herein, the phrase "incorporated into" is intended to comprise any suitable means whereby a source of the selected element is appropriately combined with the dielectric, such as by intimately adding or mixing the source into the dielectric pre-melt batch or to the melt, by ion exchange; by ion implantation; by diffusion techniques; or by applying one or more layers to the charge storage surface of the dielectric, or to the electrode contact surface of the dielectric, or as an internal layer within the dielectric.
In one particular embodiment hereof, the source of the selected element is applied as one or more layers to the chargestorage surface of the dielectric.
As used herein, the term "layer" is intended to be all inclusive of other similar terms such as film, deposit, coating, finish, spread, covering, etc.
It is contemplated that the element source may be applied as a layer over one or more previously applied dielectric layers. Likewise, one or more layers of other substances may be applied over the layer of the element source. Such other dielectric layers may comprise luminescent phosphors and/or any other suitable compounds, especially inorganic compounds of Al, Pb, Si, Ti, rare earths (e.g., thorium), Group IA (e.g., cesium), and/or Group IIA (e.g., magnesium).
The source of the selected element is applied to the dielectric surface (or over a previously applied layer) by any convenient means including not by way of limitation vapor deposition; vacuum deposition; chemical vapor deposition, wet spraying upon the surface a mixture of solution of the layer substance suspended or dissolved in a liquid followed by evaporation of the liquid; dry spraying of the layer upon the surface; thermal evaporation using direct heat, electron beam, or laser; plasma flame and/or arc spraying and/or deposition; and sputtering target techniques.
Each layer of the source of the selected transition element is applied to the dielectric, as a surface or sub-layer, in an amount sufficient to obtain the desired beneficial result, usually to a thickness of at least about 100 angstrom units, with a typical thickness range of about 200 angstrom units per layer up to about 1 micron (10,000 angstrom units) per layer.
In the fabrication of a gaseous discharge panel, the dielectric material is typically applied to and cured on the surface of a supporting glass substrate or base to which the electrode or conductor elements have been previously applied. The glass substrate may be of any suitable composition such as a soda lime glass composition. Two glass substrates containing electrodes and cured dielectric are then appropriately sealed together, e.g., using thermal means, so as to form a panel.
In one preferred practice of this invention, each element containing layer is applied to the surface of the cured dielectric before the panel heat sealing cycle, with the substrate temperature during the layer application ranging from about 150.degree. to about 600.degree. F.
In accordance with the practice of this invention, it is contemplated using any suitable source of a transition element selected from vanadium (V), niobium (Nb), tantalum(Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), palladium (Pd), and platinum (Pt).
Typical sources include the elemental form of the selected element, a mineral, and/or a compound. It is especially contemplated using inorganic compounds.
Although insulating or semi-conductor materials are typically used, conductor materials may be used if the material is appropriately isolated within or on the dielectric so as not to be in direct contact with a source of electrical potential and/or ground.
Likewise if a conductive material is used in a multiple cell device, the geometric arrangement of the material may be such that no two cells are electrically connected by the conductive material. For example, a conductive material could be deposited on a spot over each discharge site.
The selected source is typically a solid. However, liquid materials may be used, especially if applied in a suitable binder.
Typical inorganic vanadium compounds include vanadium halides such as vanadium tribromide, vanadium tetrabromide, vanadium pentabromide, vanadium carbide, vanadium dichloride, vanadium trichloride, vanadium tetrachloride, vanadium trifluoride, vanadium diiodide, vanadium triiodide, and vanadium oxides such as vanadium dioxide, vanadium tetraoxide, vanadium pentoxide, and vanadium sesquioxide. Other compounds include vanadium diboride, vanadium oxychloride, vanadium oxybromide, vanadium oxydibromide, vanadium oxydichloride, vanadium oxydifluoride, vanadium disilicide, divanandium silicide, vanadium sulfate, vanadium monosulfide, vanadium disulfide, vanadium pentasulfide, vanadium trisulfide, and vanadium sesquisulfide.
Typical inorganic niobium compounds include niobium boride, niobium pentabromide, niobium carbide, niobium pentachloride, niobium pentafluoride, niobium hydride, niobium nitride, niobium oxybromide, niobium oxychloride, niobium potassium fluoride, and niobium oxides such as niobium dioxide, niobium monixide, niobium pentoxide, niobium trioxide, and niobium sesquioxide.
Typical inorganic tantalum compounds include tantalum diboride, tantalum bromide, tantalum carbide, tantalum chloride, tantalum iodide, tantalum fluoride, tantalum pentachloride, tantalum nitride, tantalum sulfide, and tantalum oxides including tantalum pentaoxide.
Typical inorganic chromium compounds include chromium monarsenide, chrominium monoboride, chromium dibromide, chromium tribromide, chromium carbonyl, chromium dicarbide, trichromium dicarbide, chromium dichloride, chromium trichloride, chromium difluoride, chromium trifluoride, chromium diiodide, chromium triiodide, chromium dinitrate, chromium trinitrate, chromium monomitride, chromium orthophosphate, chromium pyrophosphate, chromium monophosphide, chromium silicide, chromium sulfate (II and III), chromium monosulfide, chromium sesquisulfide, chromium sulfite, and chromium oxides such as chromium dioxide, chromium monoxide, chromium sesquioxide, and chromium trioxide.
Typical inorganic molybdenum compounds include molybdenum monocarbide, molybdenum dicarbide, molybdenum diboride, molybdenum monoboride, dimolybdenum boride, dimolybdenum carbide, molybdenum carbonyl, molybdenum dichloride, molybdenum trichloride, molybdenum tetrachloride, molybdenum pentachloride, molybdenum tetraiodide, molybdenum diiodide, molybdenum hexafluoride, molybdenum oxybromide, molybdenum oxytetrachloride, molybdenum oxytrichloride, molybdenum oxydichloride, trimolybdenum oxyhexachloride, molybdenum oxytetrafluoride, molybdenum disulfide, and molybdenum oxides such as molybdenum dioxide, molybdenum trioxide, molybdenum sesquioxide, and molybdenum pentaoxide.
Typical inorganic tungsten compounds include tungsten diboride, tungsten dibromide, tungsten pentabromide, tungsten hexabromide, tungsten carbide, ditungsten carbide, tungsten hexachloride, tungsten pentachloride, tungsten dioxide, tungsten pentoxide, tungsten trioxide, tungsten oxytetrachloride, tungsten oxytetrabromide, tungsten dioxydibromide, tungsten dioxydichloride, tungsten oxytetrafluoride, tungsten silicide, tungsten trisulfide, tungsten disulfide, tungsten carbonyl, tungsten arsenide, tungsten dichloride, tungsten tetrachloride, tungsten diiodide, tungsten phosphide, ditunsten phosphide and tungsten diphosphide.
Typical inorganic manganese compounds include manganese diarsenide, manganese monoarsenide, manganese triarsenide, manganese dichloride, manganese difluoride, manganese dibromide, manganese diiodide, manganese carbide, manganese diboride, manganese monoboride, manganese pyrophosphate, manganese monophosphide, trimanganese diphosphide, manganese carbonate, manganese titanate, manganese tantalate, manganese selenate, manganese pentaselenate, manganese selenide, manganese selenite, manganese trichloride, manganese chloroplatinate, manganese chromite, manganese fluogallate, manganese fluosilicate, manganese trifluoride, manganese hydroxide, manganese hexaiodoplatinate, manganese nitrate, manganese monoxide (II and III), manganese dioxide, manganese heptoxide, manganese trioxide, manganese sesquioxide, manganese orthophosphate, manganese hypophosphite, manganese orthophosphite, manganese metasilicate, manganese monosilicide, manganese disilicide, dimanganese silicide, manganese sulfate (II and III), manganese sulfide, and manganese dithionate.
Typical inorganic technetium compounds include technetium bromide oxide, technetium chloride, technetium chloride oxide, technetium fluoride, technetium bromide, technetium oxide, technetium selenide, and technetium sulfide.
Typical inorganic rhenium compounds include rhenium bromide, rhenium pentacarbonyl, rhenium pentachloride, rhenium tetrachloride, rhenium trichloride, rhenium fluoride, rhenium hexafluoride, rhenium dioxide, rhenium heptoxide, rhenium peroxide, rhenium sesquioxide, rhenium trioxide, rhenium trioxybromide, rhenium trioxychloride, rhenium oxytetrachloride, rhenium oxytetrafluoride, rhenium dioxydifluoride, rhenium disulfide, rhenium heptasulfide, and rhenium tribromide.
Typical inorganic iron compounds include iron orthoarsenate, iron orthoarsenite, iron pyroarsenite, iron arsenide, iron diarsenide, iron boride, iron bromide, iron carbide, iron carbonate, iron ennea carbonyl, iron pentacarbonyl, iron tetracarbonyl, iron perchlorate, iron oxychloride, iron chloride, iron chloride hexammine, iron chloroplatinate, iron dichromate, iron chromite, iron ferricyanide, iron fluoride, iron fluosilicate, iron hydrogen cyanide, iron iodate, iron iodide, iron tetraiodide, iron nitrate, iron nitride, iron oxide, iron orthophosphate, iron pyrophosphate, iron monophosphide, diiron phosphide, triiron phosphide, iron hypophosphite, iron metasilicate, iron orthosilicate, iron silicide, iron sulfate, iron disulfide, iron sulfide, iron sulfite, iron tantalate, iron thiocyante, iron thiosulfate, iron tungstate, and iron metavanadate.
Typical inorganic ruthenium compounds include ruthenium tetrachloride, ruthenium trichloride, ruthenium pentafluoride, ruthenium dioxide, ruthenium tetraoxide, ruthenium hydroxide, ruthenium oxychloride, ruthenium silicide, and ruthenium sulfide.
Typical inorganic osmium compounds include oxmium carbonyl chloride, osmium dichloride, osmium tetrachloride, osmium trichloride, osmium hexafluoride, osmium tetrafluoride, osmium tetraiodide, osmium tribromide, osmium triiodide, osmium tetrabromide, osmium carbonyl bromide, osmium hexachloride, osmium dioxide (both black and brown), osmium monoxide, osmium sesquioxide, osmium tetra oxide, osmium disulfide, osmium tetra sulfide, osmium sulfite, and osmium telluride.
Typical inorganic cobalt compounds include cobalt aluminate, cobalt orthoarsenate, cobalt arsenic sulfide, cobalt arsenide, cobalt monoboride, cobalt bromate, cobalt bromide, cobalt bromoplatinate, cobalt carbonate, cobalt tetracarbonyl, cobalt basic carbonate, cobalt tricarbonyl, cobalt chlorate, cobalt perchlorate, cobalt chloride, cobalt chloroplatinate, cobalt chlorostannate, cobalt chromate, cobalt cyanide, cobalt ferricyanide, cobalt ferrocyanide, cobalt fluogallate, cobalt fluoride, cobalt fluosilicate, cobalt iodate, cobalt iodide, cobalt iodoplatinate, cobalt nitrate, cobalt oxide, cobalt orthophosphate, cobalt phosphide, cobalt perrhenate, cobalt selenate, cobalt monoselenide, cobalt orthosilicate, cobalt silicide, cobalt disilicide, dicobalt silicide, cobalt orthostannate, cobalt sulfate, cobalt disulfide, cobalt monosulfide, cobalt sesquisulfide, tricobalt sulfide, cobalt sulfite, cobalt thiocyanate, cobalt orthotitanate, cobalt tungstate, and cobalt cobalt complexes such as hexammine cobalt bromide, diammine cobalt chloride (alpha and beta), hexammine cobalt chloride, hexammine cobalt iodide, hexammine cobalt nitrate, hexammine cobalt perrhenate, hexammine cobalt sulfate, ammonium tetranitrodiammine cobaltate, aquapentamminecobalt sulfate, cis-chloroaquotetramminecobalt chloride, chloropentammine cobalt chloride, triethylenediaminecobalt chloride, trinitrotriamminecobalt, trinitrotetramminecobalt nitrate, and potassium tetranitrodiamminecobaltate.
Typical inorganic rhodium compounds include: rhodium hexamminechloride, rhodium basic carbonylchloride, rhoeium trichloride, rhodium trifluoride, rhodium triiodide, rhodium nitrate, rhodium dioxide, rhodium sesquioxide, rhodium sulfate, rhodium monosulfide, rhodium sesquisesquioxide, and rhodium sulfite.
Typical inorganic iridium compounds include iridium tetrabromide, iridium tribromide, iridium carbonyl, iridium carbonyl chloride, iridium dichloride, iridium tetrachloride, iridium trichloride, iridium hexafluoride, iridium tetraiodide, iridium triiodide, iridium dioxide, iridium sesquioxide, iridium phosphor chloride, iridium selenide, iridium sulfate, iridium disulfide, iridium monosulfide, iridium sesquisulfide, and iridium telluride.
Typical inorganic palladium compounds include palladium bromide, palladium chloride, palladium iodide, palladium cyanide palladium difluoride, palladium dichloride, palladium dibromide, palladium diiodide, palladium trichloride, palladium tribromide, palladium triiodide, palladium nitrate, palladium dioxide, palladium monoxide, palladium selenate, palladium selenide, palladium diselenide, palledium silicide, palladium sulfate, palladium disulfide, palladium monosulfide, palladium subsulfide, and palladium ditelluride.
Typical inorganic platinum compounds include platinum arsenide, platinum dibromide, platinum tetrabromide, platinum carbonyl bromide, platinum carbonyl dichloride, platinum dicarbonyl dichloride, diplatinum dicarbonyl tetrachloride, diplatinum tricarbonyl tetrachloride, platinum carbonyl diiodide, platinum carbonyl sulfide, platinum dichloride, platinum tetrachloride, platinum trichloride, platinum dicyanide, platinum dichlorocarbonyl dichloride, platinum difluoride, platinum hexafluoride, platinum tetrafluoride, platinum hydioxide, platinum diiodide, platinum tetraiodide, platinum triiodide, platinum monoxide, platinum dioxide, platinum sesquioxide, platinum trioxide, platinum pyrophosphate, platinum phosphide, platinum diselenide, platinum triselenide, platinum triselenide, platinum sulfate, platinum disulfide, platinum monosulfide, platinum sesquisulfide, platinum telluride, and platinum complexes such as tetramine platinum chloride, tetrammineplatinum and chloroplatinite.
The use of this invention has many potential benefits. For example, sources of the selected element may be used alone or in combination with other elements (such as enumerated hereinbefore) to achieve lower panel operating voltages, thermal stability, more uniform panel operating voltages, decreased aging cycle time, etc.